A manufacturing process of a semiconductor device includes a liquid processing step of etching or cleaning a substrate such as, for example, a semiconductor wafer by supplying a chemical liquid to the substrate. When the chemical liquid is supplied to the substrate at a temperature higher than a normal temperature, a chemical liquid supply system including a tank configured to store the chemical liquid and a circulation line connected to the tank is generally used. The chemical liquid within the tank is fed to the circulation line by a pump provided in the circulation line, and is returned again to the tank from the circulation line. The chemical liquid is heated by the heater unit provided in the circulation line. A branch line is connected to the circulation line, and the chemical liquid is supplied to a liquid processing unit through the branch line. The liquid processing unit performs a processing on the substrate using the supplied chemical liquid.
A power to be supplied to a heating portion of the heater unit is controlled based on a deviation between an actual temperature of the chemical liquid within the circulation line detected by a temperature sensor, and a target temperature, and by the control, the temperature of the chemical liquid within the circulation line is maintained at the target temperature. When a component member of the heater unit is overheated, the heater unit may be damaged. In particular, when a water-contact member of the heater unit is damaged, there may be a case in which the chemical liquid may be leaked, thereby causing damage to a substrate liquid processing apparatus and its surroundings. In order to prevent overheating of the component member of the heater unit, for example, Japanese Patent No. 5307780 (Japanese Patent Laid-Open Publication No. 2012-057904) provides a temperature sensor configured to detect the temperature of the component member. When the temperature of the component member exceeds a predetermined upper limit, a control is performed to stop the supply of a power to the heating portion of the heater unit.
However, when the supply of the power to the heating portion of the heater unit is stopped, there is a problem in that the temperature of the component member of the heater unit may be increased due to the residual heat of the heating portion, and thus the component member of the heater unit is overheated.